Patent GB-190205484-A (GB)
Title: Improvements in Multicolour Printing Machines.
Filed: 1902-03-05
Granted: 1902-09-18
Abstract: 5484. Printing Arts Co., Mowbray, F. S., and Black, W. March 5. Printing in several colours; etching.-Relates to improvements in multi-colour printing-machines of the class in which the separate colour designs are transferred by elastic transfer members to printing-members which impart a multi-colour print at one impression to the paper. When all the colours, dark and light, are thus transferred to one printing-member, some mingling of colours takes place, this being especially the case with half-tone and three-colour process work. Moreover, when fine letterpress appears on the coloured design, it loses sharpness in the transfer process. The improvements consist in collecting the lighter colour part-designs of the picture by transfer to one printing-member, and printing the combined design first upon the paper, and then collecting the darker coloured part-designs on another printing- member, from which a second impression is made. The printing-member for the lighter inks may be provided with a design in relief or intaglio, but is preferably plain, to prevent distortion of the paper. The part-design members may be either stereos, electros, zincs, wood-cuts, or other known kinds of printing-plate, and each is provided with an independent system of inking and distributing rollers. For three-colour work, the yellow and red may be combined for one impression, and the blue and black for the other, or the black may be printed separately. When five colours are used, the first impression is from two light colours, the second from two darker ones, and a third impression is made in a dark finishing-colour, such as black. In high-class art work, a different impression member may be used for each printing- member, in order that the " make-ready " may be properly adapted for each impression; but for general work this is not required, the printing- members being truly ground and polished to the correct printing-line before etching. In the case of curved plates, photographically-prepared flexible negatives may be used instead of glass, the etching being effected by rocking the carrier on which the plate is mounted, so as to subject the plate to the action of a suitable etching-fluid. Rotary or cylinder machines may be used, and they may be arranged for sheet or web feed, and for single-side printing or perfecting. Fig. 1 is a diagram showing the arrangement of a rotary machine for multicolour printing on separate sheets. The carrier A receives three part-design members G, H, I, each inked in its proper colour by rolls 1, 2, &c. The colour designs are transferred in correct register to the printing-member Z by means of transfer members 0, P, Q. The impression-bed carrier D is provided with one impression member Y, and with suitable gripping-mechanism to hold the sheets fed in at F. The carrier B may carry one part-design member J for a dark colour, and the black part-design or letterpress may be printed from a member K on a third carrier C. When more colours are used, the rolls R, S, T may transfer colours from the members L, M, N to the printing-member J. Fig. 2 shows a web-printing perfecting-machine, in which transfer printing in three colours is effected by the member Z, and a printing-member J gives the finishing-colour or black to the design. Members L, M, N may serve to print letterpress pages, and may be inked in two colours, say, black and brown. The web w passes round a second imrression cylinder R, the printed side being in contact with the off-set web X. The other side is printed by members S, T, U, V on the carrier W, alternate pages being printed in two colours if desired. The inking-rollers are mounted in spring-pressed bearings, and are lifted to clear members which are not to be inked by them. This is effected by cam pieces in the usual way. Printing-members such as Z are of greater height than the members G, H, I. Combined rotary and cylinder machines may be used, the multi-colour design being printed as described above, and the black type matter or letterpress being printed by the passage of a flat plate or forme beneath the impression cylinder.